newbies need sum help..

hi im engr. Student.. H0pe u help me with this .. Can any0ne s0lve this using law 0f c0sine: (my pr0f. Said that it can be d0ne by the said law)1. If the sl0wer ship in the preseding exercise leaves at noon, and the other at 1p.m., how far apart are they at 2p.m.?2.three circles 0f radii 3,4,and 5 inches respectively are tangent t0 each 0ther externally. Find the angles 0f the triangle f0rmed by j0ining the centers.Can any give the s0luti0n with figure s0 i will understand it .. Tnx in advance )

Re: newbies need sum help..

For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines: $\displaystyle C^2 = A^2 + B^2 - 2AB \cos(c)$ You have values for A, B and C, so solve for $\displaystyle \cos(c) $ and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.[/QUOTE] CanU please figure it out .. how it the 3 sides became 7,8,9 ?? can u give the figure?